Articles including anticondensation and/or low-E coatings and/or methods of making the same

ABSTRACT

Certain example embodiments of this invention relate to articles including anticondensation and/or low-E coatings that are exposed to an external environment, and/or methods of making the same. In certain example embodiments, the anticondensation and/or low-E coatings may be survivable in an outside environment. The coatings also may have a sufficiently low sheet resistance and hemispherical emissivity such that the glass surface is more likely to retain heat from the interior area, thereby reducing (and sometimes completely eliminating) the presence condensation thereon. The articles of certain example embodiments may be, for example, skylights, vehicle windows or windshields, IG units, VIG units, refrigerator/freezer doors, and/or the like.

This application is a Continuation-in-Part (CIP) of U.S. patentapplication Ser. No. 12/926,714, filed Dec. 6, 2010, which is a CIP ofU.S. patent application Ser. No. 12/923,082, filed Aug. 31, 2010, andSer. No. 12/662,894, filed May /10/2010, the latter of which is a CIP ofSer. No. 12/659,196, filed Feb. 26, 2010, the disclosure of each ofwhich are hereby incorporated herein by reference.

FIELD OF THE INVENTION

Certain example embodiments of this invention relate to articlesincluding anticondensation and/or low-E coatings, and/or methods ofmaking the same. More particularly, certain example embodiments of thisinvention relate to articles including anticondensation and/or low-Ecoatings that are exposed to an external environment, and/or methods ofmaking the same. In certain example embodiments, the anticondensationand/or low-E coatings may be survivable in an outside environment andalso may have a low hemispherical emissivity such that the glass surfaceis more likely to retain heat from the interior area, thereby reducing(and sometimes completely eliminating) the presence condensationthereon. The articles of certain example embodiments may be, forexample, skylights, vehicle windows or windshields, IG units, VIG units,refrigerator/freezer doors, and/or the like.

BACKGROUND AND SUMMARY OF EXAMPLE EMBODIMENTS OF THE INVENTION

Moisture is known to condense on skylights, refrigerator/freezer doors,vehicle windows, and other glass products. Condensation buildup onskylights detracts from the aesthetic appeal of the lite. Similarly,condensation buildup on refrigerator/freezer doors in supermarkets orthe like sometimes makes it difficult for shoppers to quickly and easilypinpoint the products that they are looking for. And condensationbuildup on automobiles often is an annoyance in the morning, as a driveroftentimes must scrape frost or ice and/or actuate the vehicle'sdefroster and/or windshield wipers to make it safer to drive. Moistureand fog on the windshield oftentimes presents a similar annoyance,although they may also pose potentially more significant safety hazardsas a driver traverses hilly areas, as sudden temperature drops occur,etc.

Various anticondensation products have been developed over the years toaddress these and/or other concerns in a variety of applications. See,for example, U.S. Pat. Nos. 6,818,309; 6,606,833; 6,144,017; 6,052,965;4,910,088, the entire contents of each of which are hereby incorporatedherein by reference. As alluded to above, certain approaches use activeheating elements to reduce the buildup of condensation, for example, asin vehicle defrosters, actively heated refrigerator/freezer doors, etc.These active solutions unfortunately take time to work in the vehiclecontext and thus address the problem once it has occurred. In the caseof refrigerator/freezer doors, such active solutions may be expensiveand/or energy inefficient.

Some attempts have been made to incorporate a thin-film anticondensationcoating on a window. These attempts generally have involvedpyrolitically depositing a 4000-6000 angstrom thick fluorine-doped tinoxide (FTO) coating on the exterior surface (e.g., surface 1) of awindow such as, for example, a skylight. Although pyrolytic depositiontechniques are known to present “hard coatings,” the FTO unfortunatelyscratches fairly easily, changes color over time, and suffers from otherdisadvantages.

Thus, it will be appreciated there is a need in the art for articlesincluding improved thin-film anticondensation and/or low-E coatings,and/or methods of making the same.

One aspect of certain example embodiments relates to anticondensationand/or low-E coatings that are suitable for exposure to an externalenvironment, and/or methods of making the same. The external environmentin certain example instances may be the outside and/or the inside of avehicle or house (as opposed to, for example, a more protected areabetween adjacent substrates).

Another aspect of certain example embodiments relates toanticondensation and/or low-E coatings that have a low sheet resistanceand a low hemispherical emissivity such that the glass surface is morelikely to retain heat from the interior area, thereby reducing (andsometimes completely eliminating) the presence condensation thereon.

Still another aspect of certain example embodiments relates to coatedarticles having an anticondensation and/or low-E coating formed on anouter surface and one or more low-E coatings formed on one or morerespective interior surfaces of the article. In certain exampleembodiments, the anticondensation coating may be thermally tempered(e.g., at a temperature of at least 580 degrees C. for at least about 2minutes, more preferably at least about 5 minutes) or annealed (e.g., ata temperature lower than that required for tempering).

The articles of certain example embodiments may be, for example,skylights, vehicle windows or windshields, IG units, VIG units,refrigerator/freezer doors, and/or the like.

Certain example embodiments of this invention relate to a skylightcomprising: first and second substantially parallel, spaced apart glasssubstrates; a plurality of spacers arranged to help maintain the firstand second substrates in substantially parallel, spaced apart relationto one another; an edge seal sealing together the first and secondsubstrates; and an anticondensation coating provided on an exteriorsurface of the first substrate exposed to an environment external to theskylight, the anticondensation coating comprising the following layersmoving away from the first substrate: a layer comprising silicon nitrideand/or silicon oxynitride, a layer comprising a transparent conductiveoxide (TCO), a layer comprising silicon nitride, and a layer comprisingat least one of zirconium oxide, zirconium nitride, aluminum oxide, andaluminum nitride, wherein the anticondensation coating has ahemispherical emissivity of less than less than 0,23 and a sheetresistance of less than 30 ohms/square. The TCO may be of or includingITO or the like in certain example embodiments of this invention.

Certain example embodiments of this invention relate to a skylight.First and second substantially parallel, spaced apart glass substratesare provided. A plurality of spacers are arranged to help maintain thefirst and second substrates in substantially parallel, spaced apartrelation to one another. An edge seal helps seal together the first andsecond substrates. An anticondensation coating is provided on anexterior surface of the first substrate exposed to an environmentexternal to the skylight. The anticondensation coating comprises thefollowing thin-film layers deposited in the following order moving awayfrom the first substrate: a silicon-inclusive barrier layer, a firstsilicon-inclusive contact layer, a layer comprising a transparentconductive oxide (TCO), a second silicon-inclusive contact layer, and alayer of zirconium oxide. The anticondensation coating has ahemispherical emissivity of less than less than 0.23 and a sheetresistance of less than 30 ohms/square.

Certain example embodiments of this invention relate to a coated articlecomprising: a coating supported by a substrate, wherein the coating isan anticondensation coating comprising the following layers moving awayfrom the first substrate: a layer comprising silicon nitride and/orsilicon oxynitride, a layer comprising a transparent conductive oxide(TCO), a layer comprising silicon nitride, and a layer comprising one ormore of zirconium oxide, zirconium nitride, aluminum oxide, and aluminumnitride, wherein the anticondensation coating is disposed on an exteriorsurface of the substrate such that the anticondensation coating isexposed to an external environment, and the anticondensation coating hasa hemispherical emissivity of less than less than 0.23 and a sheetresistance of less than 30 ohms/square.

Certain example embodiments of this invention relate to a coated articlecomprising a coating supported by a substrate. The coating is ananticondensation coating comprising the following thin-film layersdeposited in the following order moving away from the first substrate: asilicon-inclusive barrier layer, a first silicon-inclusive contactlayer, a layer comprising a transparent conductive oxide (TCO), a secondsilicon-inclusive contact layer, and a layer of zirconium oxide. Theanticondensation coating is disposed on an exterior surface of thesubstrate such that the anticondensation coating is exposed to anexternal environment. The anticondensation coating has a hemisphericalemissivity of less than less than 0.23 and a sheet resistance of lessthan 30 ohms/square.

According to certain example embodiments, the external environment isthe inside of a house or vehicle. According to certain exampleembodiments, the external environment is the outside environment.According to certain example embodiments, a low-E coating is provided onthe substrate opposite the anticondensation coating.

In certain example embodiments, the coated article may be built into askylight, window, insulating glass (IG) window, vacuum insulating glass(VIG) window, refrigerator/freezer door, and/or vehicle window orwindshield. The anticondensation coating may be provided on surface oneand/or surface four of an IG or VIG unit, for example.

In certain example embodiments, a method of making an insulating glassunit (IGU) is provided. A first glass substrate is provided. A pluralityof layers is disposed, directly or indirectly, on a first major surfaceof the first glass substrate, the plurality of layers including, inorder moving away from the first glass substrate: a first layercomprising silicon oxynitride having an index of refraction of 1.5-2.1,a layer comprising ITO having an index of refraction of 1.7-2.1, and asecond layer comprising silicon oxynitride having an index of refractionof 1.5-2.1. The first glass substrate is heat treated with the pluralityof layers disposed thereon. A second glass substrate is provided insubstantially parallel, spaced apart relation to the first glasssubstrate such that the first major surface of the first glass substratefaces away from the second glass substrate. The first and second glasssubstrates are sealed together.

According to certain example embodiments, the first and second layercomprising silicon oxynitride have indices of refraction of 1.7-1.8and/or the layer comprising ITO has an index of refraction of 1.8-1.93.

According to certain example embodiments, said heat treating involveslaser annealing, exposure to NIR-SWIR radiation, and/or furnace heating.

In certain example embodiments, a method of making an insulating glassunit (IGU) is provided. A first glass substrate is provided. A pluralityof layers is disposed, directly or indirectly, on a first major surfaceof the first glass substrate, with the plurality of layers including, inorder moving away from the first glass substrate: a first layercomprising silicon oxynitride, a layer comprising ITO, and a secondlayer comprising silicon oxynitride. The first glass substrate is heattreated with the plurality of layers disposed thereon. A second glasssubstrate is provided in substantially parallel, spaced apart relationto the first glass substrate such that the first major surface of thefirst glass substrate faces away from the second glass substrate. Thefirst substrate with the plurality of layers on the first major surfaceof the first glass substrate has a hemispherical emissivity of less thanor equal to about 0.20 and a sheet resistance less than or equal toabout 20 ohms/square following said heat treating.

In certain example embodiments, an insulating glass unit (IGU) isprovided. The IGU includes a first glass substrate. A plurality oflayers is sputter-disposed, directly or indirectly, on a first majorsurface of the first glass substrate, the plurality of layers including,in order moving away from the first glass substrate: a first layercomprising silicon oxynitride having an index of refraction of 1.5-2.1,a layer comprising ITO having an index of refraction of 1.7-2.1, and asecond layer comprising silicon oxynitride having an index of refractionof 1.5-2.1. A second glass substrate is provided in substantiallyparallel, spaced apart relation to the first glass substrate, with thefirst major surface of the first glass substrate facing away from thesecond glass substrate when assembled. An edge seal seals together thefirst and second glass substrates. The first glass substrate is heattreated with the plurality of layers disposed thereon. The firstsubstrate with the plurality of layers on the first major surface of thefirst glass substrate has a hemispherical emissivity of less than orequal to about 0.20 and a sheet resistance less than or equal to about20 ohms/square following said heat treating.

In certain example embodiments, an insulating glass (IG) unit isprovided. First and second substantially parallel spaced apart glasssubstrates are provided, with the first and second substrates providing,in order, first through fourth substantially parallel major surfaces ofthe IG unit. A gap is defined between the first and second substrates. Afourth surface of the IG unit supports a first low-E coating comprisinga plurality of thin film layers including, in order moving away from thesecond substrate: a first layer comprising silicon oxynitride having anindex of refraction of 1.5-2.1 and being 50-90 nm thick, a layercomprising ITO having an index of refraction of 1.7-2.1 and being 85-125nm thick, and a second layer comprising silicon oxynitride having anindex of refraction of 1.5-2.1 and being 50-90 nm thick.

In certain example embodiments, there is provided a coated articlecomprising a substrate supporting first and second low-E coatings onopposing major surfaces thereof, respectively. The first low-E coatingcomprises, in order moving away from the substrate: a first layercomprising silicon oxynitride having an index of refraction of 1.5-2.1and being 50-90 nm thick, a layer comprising ITO having an index ofrefraction of 1.7-2.1 and being 85-125 nm thick, and a second layercomprising silicon oxynitride having an index of refraction of 1.5-2.1and being 50-90 nm thick. The second low-E coating comprises, in ordermoving away from the substrate: a first silicon-based layer, a firstdielectric layer, a second dielectric layer split by a third dielectriclayer so as to form first and second portions of the second dielectriclayer, the third dielectric layer comprising either titanium oxide ortin oxide, a metallic or substantially metallic infrared (IR) reflectinglayer over and directly contacting the second portion of the seconddielectric layer, an upper contact layer comprising an oxide of Niand/or Cr directly over and contacting the IR reflecting layer, a fourthdielectric layer, and a second silicon-based layer.

In certain example embodiments, a method of making an insulating glassunit (IGU) is provided. A first glass substrate is provided. A firstlow-E coating is disposed, directly or indirectly, on a first majorsurface of the first glass substrate. The first low-E coating comprisesa plurality of thin film layers including, in order moving away from thefirst glass substrate: a first layer comprising silicon oxynitride, alayer comprising ITO, and a second layer comprising silicon oxynitride.A second glass substrate is provided in substantially parallel, spacedapart relation to the first glass substrate such that the first majorsurface of the first glass substrate faces away from the second glasssubstrate. The first substrate with only the first low-E coating thereonhas a hemispherical emissivity of less than or equal to about 0.20 and asheet resistance less than or equal to about 20 ohms/square followingheat treatment. The first major surface of the first glass substratecorresponds to an interior surface of the IGU.

The features, aspects, advantages, and example embodiments describedherein may be combined to realize yet further embodiments.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other features and advantages may be better and morecompletely understood by reference to the following detailed descriptionof exemplary illustrative embodiments in conjunction with the drawings,of which:

FIG. 1 is a coated article including an anticondensation coating inaccordance with an example embodiment;

FIG. 2 is an insulating glass unit including an anticondensation coating(e.g., from any embodiment of this invention such as from the FIG. 1and/or FIG. 6 embodiment) disposed on an outermost surface exposed tothe exterior atmosphere in accordance with an example embodiment;

FIG. 3 is an insulating glass unit including an anticondensation coating(e.g., from any embodiment of this invention such as from the FIG. 1and/or FIG. 6 embodiment) disposed on an innermost surface exposed tothe interior environment in accordance with an example embodiment;

FIG. 4 is an insulating glass unit including anticondensation coatings(e.g., from any embodiment of this invention such as from the FIG. 1and/or FIG. 6 embodiment) disposed on outermost and innermost surfacesof the insulating glass unit in accordance with an example embodiment;

FIG. 5 is a graph illustrating the performance of an example embodiment,a current anticondensation product, and a bare glass substrate as thetemperature, humidity, and dew point change over an 18 hour time period;

FIG. 6 is a coated article including an anticondensation coating inaccordance with an example embodiment of this invention;

FIG. 7 is a coated article including an anticondensation coating inaccordance with an example embodiment; and

FIG. 8 is a schematic view of a system incorporating an IR heater inaccordance with certain example embodiments.

DETAILED DESCRIPTION OF EXAMPLE EMBODIMENTS OF THE INVENTION

Referring now more particularly to the accompanying drawings in whichlike reference numerals indicate like parts in the several views.

Certain example embodiments of this invention relate to thin-filmanticondensation coatings that are exposed to the environment. Suchcoatings have a low hemispherical emissivity in certain exampleembodiments, which helps the glass surface retain heat provided from theinterior side. For instance, in skylight and/or other building windowexample applications, the glass surface retains more heat from theinterior of the building. In vehicle example applications, thewindshield retains more heat from the interior of the vehicle. Thishelps reduce (and sometimes even prevent) the initial formation ofcondensation. As alluded to above, such anticondensation coatings may beprovided on a surface (or multiple surfaces) exposed to the environmentin certain example instances. As such, the anticondensation coatings ofcertain example embodiments may be robust so as to be able to survivesuch conditions.

FIG. 1 is a coated article including an anticondensation coating inaccordance with an example embodiment. The FIG. 1 example embodimentincludes a glass substrate 1 supporting a multilayer thin-filmanticondensation coating 3. The anticondensation coating 3 has a lowhemispherical emissivity. In certain example embodiments, thehemispherical emissivity is less than 0.25, more preferably less than0.23, still more preferably less than 0.2, and sometimes even less than1.0-1.5. This is achieved by providing a thin transparent conductiveoxide layer (TCO) 5 such that a suitably low sheet resistance isachieved. In the FIG. 1 example, the TCO 5 is indium tin oxide (ITO). Asheet resistance of the 10-30 ohms/square generally will be sufficientto achieve the desired hemispherical emissivity values. Certain exampleembodiments described herein provide a sheet resistance of 13-27ohms/square, with the example provided below providing a sheetresistance of 17 ohms/square. In certain example instances, it ispossible to select a TCO 5 such that the sheet resistance drops to aslow as about 5 ohms/square, although this low value is not need in allembodiments of this invention. FIG. 6 illustrates a coated articleincluding similar layers, except that in the FIG. 6 embodiment layers 11and 13 are not present. In the FIG. 6 embodiment, silicon oxynitrideinclusive layer 9 b may be both a silicon-inclusive barrier layer and alower contact layer, and make be made up of a combination of layers 9 band 11 from the FIG. 1 embodiment. In the FIG. 1 and FIG. 6 embodiments,the overcoat layer 7 may be of or include zirconium oxide, aluminumoxide, aluminum nitride, and/or aluminum oxynitride in exampleembodiments of this invention. The layers 9 a, 9 b and 11 of orincluding silicon nitride and/or silicon oxynitride may be doped withaluminum (e.g., from about 0.5 to 5% Al) in certain example embodiments,as is known in the art, so that the target can be conductive duringsputtering of the layer.

Referring to FIGS. 1 and 6, the TCO 5 is protected from the environmentby a layer or zirconium oxide 7. A silicon-inclusive barrier layer 11may be provided between the TCO5 and the substrate 1 also to helpprotect the TCO 5, e.g., from sodium migration. In the FIG. 1 example,the silicon-inclusive barrier layer 11 is silicon nitride, and thesilicon nitride barrier layer 11 is provided adjacent to a layer oftitanium oxide 13. The silicon nitride barrier layer 11 and the layer oftitanium oxide 13 help with the optics of the overall article. It willbe appreciated that a low/high/low layer stack system also may be usedto improve the optics of the end product in certain example instances.In certain example embodiments, the silicon nitride barrier layer 11 maybe oxided, e.g., so that it is a layer of silicon oxynitride. In otherwords, layer 11 may be of or include silicon oxynitride for example incertain example embodiments. In certain example embodiments, a barrierlayer comprising silicon nitride (e.g., Si₃N₄ or other suitablestoichiometry) may replace the silicon-inclusive barrier layer 11 andthe titanium oxide layer 13 in the FIG. 1 example.

Additional silicon-inclusive layers 9 a and 9 b may sandwich the TCO 5.As shown in the FIG. 1 example, the upper silicon-inclusive layer 9 a isa layer of silicon nitride, whereas the lower silicon-inclusive layer 9b is a layer of silicon oxynitride. It will be appreciated that anysuitable combination of silicon with oxygen and/or nitrogen may be usedin different embodiments of this invention.

The following table provides example physical thicknesses and thicknessranges for the FIG. 1 example embodiment:

Example Thickness Range (nm) Example Thickness (nm) ZrOx (7) 2-15 7 SiNx(9a) 10-50  30 ITO (5) 75-175 130 SiOxNy (9b) 10-50  35 TiOx (13) 2-103.5 SiNx (11) 10-20  13

The thicknesses for the layers 9 b, 5, 9 a and 7 for the FIG. 6embodiment are similar and the above table is also applicable to thoselayers. However, in the FIG. 6 embodiment, silicon nitride and/orsilicon oxynitride based layer 9 b may be thicker, e.g., from about10-200 nm thick, more preferably from about 10-100 nm thick. Asindicated above, other TCOs may be used in place of, or in addition to,ITO. For instance, certain example embodiments may incorporate anITO/Ag/ITO sandwich. Certain example embodiments, may incorporate zincoxide, aluminum-doped zinc oxide (AZO), p-type aluminum oxide, doped orun-doped Ag, FTO, and/or the like. When Ag is incorporated into thelayer stack system as a TCO, layers comprising Ni and/or Cr may beprovided directly adjacent (contacting) the Ag. In certain exampleembodiments, each layer in the layer stack system may besputter-deposited. In certain example embodiments, one or more layersmay be deposited using a different technique. For instance, when FTO isincorporated as the TCO 5, it may be pyrolytically deposited (e.g.,using combustion vapor deposition or CVD).

In certain example embodiments, layer of diamond-like carbon (DLC) maybe provided directly over and contacting the zirconium oxide. This mayhelp to create a more survivable, hydrophilic-like coating in certainexample instances. Hydrophilic coatings generally involve a contactangle of less than or equal to 10 degrees. Sputter-deposited zirconiumoxide tends to have a contact angle of less than about 20 degrees.However, forming DLC on top of the DLC on top of the zirconium oxidehelps with its wettability and creates a harder layer. When tempered,for example, a zirconium oxide/DLC layer stack reaches a contact angleof less than or equal to about 15 degrees. Thus, a survivable,hydrophilic-like coating may be achieved. It is noted that this layermay be created by providing a layer of zirconium nitride followed by alayer of DLC which, upon tempering, will produce a layer of zirconiumoxide followed by a layer of DLC. See, for example, applicant Ser. No.12/320,664, which describes a heat treatable coated article includingDLC and/or zirconium in its coating. The entire contents of thisapplication are hereby incorporated herein by reference.

In addition or in the alternative, in certain example embodiments, athin hydrophilic and/or photocatalytic coating may be provided over thezirconium oxide. Such a layer may comprise anatase TiO₂, BiO, BiZr,BiSn, SnO, and/or any other suitable material. Such a layer also mayhelp with wettability and/or provide self-cleaning properties to thearticle.

In certain example embodiments, the zirconium oxide protective layer 7may be replaced with aluminum oxide and/or aluminum oxynitride.Additionally, in certain example embodiments, the layer 7 may beinitially deposited in multi-layer form so as to include a first layerof or including zirconium nitride directly on silicon nitride inclusivelayer 9 a, and a second layer of or including diamond-like carbon (DLC).Then, when heat treatment (e.g., thermal tempering including at atemperature(s) of at least about 580 degrees C.) is desired, the coatedarticle is heat treated and the overlying DLC inclusive layer burns offduring heat treatment and the zirconium nitride inclusive layertransforms into zirconium oxide thereby resulting in a heat treatedcoated article having a heat treated layer stack where the layer 7 is ofor includes zirconium oxide (e.g., see FIGS. 1 and 6).

Although not shown in the FIG. 1 or FIG. 6 examples, a silver-basedlow-E coating may be provided on the glass substrate opposite theanticondensation coating 3. For example, the silver-based low-E coatingmay be any one of the low-E coatings described in U.S. Pat. Nos.8,017,243; 7,858,191; or 7,964,284, or U.S. Publication Nos.2009/0205956 or 2010/0075155, the entire contents of which are herebyincorporated herein by reference. Of course, other low-E coatingscommercially available from the assignee of the instant invention and/orother low-E coatings also may be used in connection with differentembodiments of this invention. For instance, other suitable low-Ecoatings are described in, for example, U.S. Pat. Nos. 7,455,910;7,771,571; 7,166,359; 7,189,458; 7,198,851; 7,419,725; 7,521,096; and7,648,769; as well as U.S. Publication Nos. 2007/0036986; 2007/0036990;2007/0128451; 2009/0324967; 2010/0279144; 2010/0295330; 2011/0097590;2011/0117371; 2011/0210656; 2011/0212311; and 2011/0262726; and U.S.application Ser. No. 13/064,066, filed on Mar. 3, 2011; Ser. No.13/183,833, filed on Jul. 15, 2011; and Ser. No. 13/317,176, filed onOct. 12, 2011. The entire contents of each of these patent documents ishereby incorporated herein by reference. It will be appreciated thatsilver-based and non-silver-based low-E coatings may be used inconnection with certain example embodiments. It may sometimes beadvantageous to use non-silver-based low-E coatings for durabilitypurposes, and/or to provide heat treatable coatings. In some cases, itmay be desirable to provide a coating with comparable sheet resistanceand emissivity values to those provided above without including anAg-based layer.

When the coated article is tempered, it may be run through a temperingfurnace “face down.” In other words, when the coated article istempered, the anticondensation coating may face the rollers.

In certain example embodiments, the visible transmission may be highwhen an anticondensation coating is applied. For example, in certainexample embodiments, the visible transmission preferably will be atleast about 50%, more preferably at least about 60%, still morepreferably at least about 65%. In certain example embodiments, thevisible transmission may be 70%, 80%, or even higher.

The coated article shown in FIG. 1 or FIG. 6 may be incorporated into ainsulating glass (IG) unit. For example, FIG. 2 is an insulating glassunit including an anticondensation coating disposed on an outermostsurface exposed to the exterior atmosphere in accordance with an exampleembodiment. The IG unit in the FIG. 2 example includes first and secondsubstantially parallel spaced apart glass substrates 1 and 21. Thesesubstrates define a space or gap 22 therebetwen. The first and secondsubstrates 1 and 21 are sealed using an edge seal 23, and a plurality ofpillars 25 help maintain the distance between the first and secondsubstrates 1 and 21. The first substrate 1 supports the anticondensationcoating 3. As will be appreciated from the FIG. 2 example embodiment,the anticondensation coating 3 is exposed to the exterior environment.This is a departure from common practices, where low-E coatingsgenerally are protected from the external environment. The FIG. 2arrangement becomes possible because of the durability of theanticondensation coating 3.

Although not shown in FIG. 2, similar to as described above, a low-Ecoating (e.g., a silver-based low-E coating) may be provided on aninterior surface of one of the first and second substrates 1 and 21. Inother words, although not shown in FIG. 2, a low-E coating may beprovided on surface 2 or surface 3 of the IG unit shown in FIG. 2.

When the FIG. 2 example embodiment is provided in connection with askylight application, for example, the outer substrate 1 may be temperedand the inner substrate 21 may be laminated, e.g., for safety purposes.This may be true of other IG unit products, as well, depending on thedesired application. In addition, it will be appreciated that the IGunit structure shown in the FIG. 2 example may be used in connectionwith generally vertical and generally horizontal applications. In otherwords, the IG unit structure shown in the FIG. 2 example may be used inrefrigerator; freezer doors that are either generally upright orgenerally horizontal.

In certain example embodiments, the space or gap 22 between the firstand second substrates 1 and 21 may be evacuated and/or filed with aninert gas (such as argon, for example), and the edge seal 23 may providean hermetic seal, e.g., in forming a vacuum insulated glass (VIG) unit.

FIG. 2 shows an IG unit having two glass substrates. However, theexample anticondensation coatings described herein may be used inconnection with products that contain first, second, and thirdsubstantially parallel and spaced apart glass substrates (also sometimesreferred to as “triple-glaze” products). The anticondensation coatingmay be disposed on surface 1 (the outermost surface exposed to theenvironment), and low-E coatings may be disposed on one or more interiorsurfaces (surfaces other than surface 1 and surface 6). For example, theanticondensation coating may be disposed on surface 1, and low-Ecoatings may be disposed on surfaces 2 and 5, 3 and 5, etc., indifferent embodiments of this invention. Such triple-glaze products maybe IG units containing three lites or substrates, triple VIG unitscontaining three lites or substrates, etc., in different embodiments ofthis invention. Triple glaze IG units are disclosed, for example, inU.S. application Ser. No. 13/324,267, filed on Dec. 13, 2011, the entirecontents of which is incorporated herein by reference.

As indicated above, certain example embodiments may be used inconnection with vehicle windshields, windows, mirrors, and/or the like.The hemispherical emissivity of the exterior glass surfaces of a vehicletypically is greater than about 0.84. However, by reducing thehemispherical emissivity to the above-identified (and/or other) ranges,the glass surface may retain more heat provided by the interior of thevehicle. This, in turn, may result in reduced or eliminated condensationbuildup on the lite surface when a moving vehicle goes from colder towarmer climate (e.g., in hilly areas), reduced or eliminatedcondensation and/or frost buildup on the lite when parked and left overnight, etc. The anticondensation coating in vehicle applications may beprovided on the side of the glass that is exterior to the vehicle cabin.

The zirconium oxide topcoat is advantageous for vehicle windowapplications, as it has a comparatively low coefficient of friction.More particularly, this lower coefficient of friction facilitates theupward and downward movement of windows.

Certain example embodiments may be used in connection with any suitablevehicle including, for example, automobiles; trucks; trains; boats,ships and other vessels; airplanes; tractors and other work equipment;etc. In vehicle mirror applications, the optics of the coating may betune such that a “double reflection” does not occur.

The inventors of the instant application have also realized that theanticondensation coating of certain example embodiments may be used tohelp meet the so-called “0.30/0.30 standard.” Briefly, the 0.30/0.30standard refers to a U-value of less than or equal to 0.30 and a solarheat gain coefficient (SHGC) of less than or equal to 0.30. Currentlegislation in the U.S. would give a tax credit for investing inwindows, skylights, doors, etc., that meet these criteria.

FIG. 3 is an insulating glass unit including an anticondensation coating(e.g., see the coating of FIG. 1 and/or FIG. 6) disposed on an innermostsurface exposed to the interior environment in accordance with anexample embodiment. The FIG. 3 example embodiment is similar to the FIG.2 example embodiment, except that the FIG. 3 example embodiment has theanticondensation coating 3 located on surface 4, which is the exteriorsurface of the inner glass substrate 1 that is exposed to the buildinginterior rather than the outside environment.

In certain example embodiments, the inner substrate 1 may be annealed(rather than tempered). The anticondensation coating may remain the sameor substantially the same as between the FIG. 2 and FIG. 3 exampleembodiments, although the modifications described above in connectionwith FIGS. 1, 2 and/or 6 also may be made in connection with anembodiment like FIG. 3. One change that might be made is increasing thethickness of the ITO to achieve the desired U-value performance. In suchcases where the ITO is thickened, the thicknesses of the other layersmay also be adjusted so that the desired optical properties areachieved. Additional layers also may be added to achieve the desiredoptical properties. The other structural elements remain the same asbetween FIGS. 2 and 3, and similar modifications may be made thereto.

When the anticondensation coating 3 is disposed on surface 4 as shown inFIG. 3, the U-value has been determined to be 0.29. When an additionallow-E coating is provided on surface 2 of the IG unit, the U-value hasbeen found to drop to 0.23. Certain example embodiments also may providea SHGC less than or equal to 0.30, thereby helping meet the 0.30/.30standard.

In products with low U-values (e.g., IG or VIG units with theanticondensation coating on surface 4, two- and three-lite VIG units,etc.), condensation can become a problem, e.g., as the glass is notheated because of the low-emissivity coatings. One solution to thischallenge is presented in FIG. 4, which is an insulating glass unitincluding anticondensation coatings disposed on outermost and innermostsurfaces of the insulating glass unit in accordance with an exampleembodiment. In the FIG. 4 example, first and second substrates 1 a and 1b are provided. First and second anticondensation coatings 3 a and 3 bare provided on surfaces 1 and 4, respectively. In certain exampleembodiments, additional low-E coatings also may be provided on one orboth of the inner surfaces (surfaces 2 and/or 3). In this way, it ispossible to provide a product that exhibits U-value reduction andanticondensation behaviors.

FIG. 5 is a graph illustrating the performance of an example embodiment,a current anticondensation product, and a bare glass substrate as thetemperature, humidity, and dew point change over an 18 hour time period.The images in FIG. 5 each have a “crisscross” pattern printed thereon tohelp demonstrate the presence or absence of condensation. As can be seenfrom FIG. 5, there is virtually no condensation formed on those samplesthat were produced in accordance with an example embodiment. Bycontrast, the comparative example, which includes pyrolyticallydeposited FTO, shows some condensation being formed in the firstobserved period, with the level of condensation greatly increasingthrough the second and third observed periods, and abating slightly bythe fourth observed period. Indeed, the “crisscross” pattern issignificantly blurry at the second observed period and barely visibleduring the third. The uncoated glass sample shows significantcondensation during all observed periods. The “crisscross” pattern inthe second and third observed periods cannot be seen. The FIG. 5 examplethus demonstrates that the example embodiments described herein providesuperior performance when compared to the current comparative exampleand uncoated glass.

FIG. 7 is a coated article including an anticondensation coating inaccordance with an example embodiment. The FIG. 7 example layer stack issimilar to the previously described example layer stacks in that itincludes a TCO layer 5 sandwiched by first and second silicon-inclusivelayers 9 a and 9 b. In the FIG. 7 example embodiment, the first andsecond silicon-inclusive layers 9 a and 9 b comprises siliconoxynitride. The first and second layers comprising silicon oxynitride 9a and 9 b sandwich a TCO layer 5 comprising ITO. Example thicknesses andindices of refraction for each of the layers is provided in the tablethat follows:

Example First Second Example Preferred First Second Thickness ExampleExample Index of Index of Example Example Range Thickness ThicknessRefraction Refraction Index of Index of (nm) (nm) (nm) Range RangeRefraction Refraction SiO_(x)N_(y) 30-100 60 70 1.5-2.1 1.7-1.8 1.75 1.7ITO 95-160 105 105 1.7-2.1  1.8-1.93 1.88 1.9 SiO_(x)N_(y) 30-100 65 701.5-2.1 1.7-1.8 1.75 1.7 Glass N/A N/A N/A N/A N/A N/A N/A

Other variants of this layer stack are possible in different embodimentsof this invention. Such variants may include, for example, usingpartially or fully oxided and/or nitrided layers for the first and/orsecond silicon-inclusive layers, adding a protective overcoat comprisingZrOx, adding one or more index matching layers (e.g., comprising TiOx)between the glass substrate and the second silicon-inclusive layer, etc.For instance, certain example embodiments may involve modifying to FIG.7 example layer stack so as to replace the top layer comprising SiOxNywith SiN, add a layer comprising ZrOx (e.g., to potentially increasedurability), both replace the top layer comprising SiOxNy with SiN andadd a layer comprising ZrOx, etc. Thus, it will be appreciated that thepossible modifications listed herein may be used in any combination orsub-combination.

Modifications also may be made to meet the so-called “R5 window” rating(whole window U-value<0.225) with a low emissivity (e.g., <0.20). Tomeet such standards, the thickness of the TCO layer may be increased.Projected ITO thickness increases and performance metrics are providedin the table below. It will be appreciated that the silicon-inclusivelayers may also be adjusted to maintain acceptable optics, and/or thatdielectric layers such as layers comprising titanium oxide may be added.It is noted that the glass substrates are assumed to be 3 mm clear glasssubstrates, that a low-E coating is provided on surface 2, and that a ½″gap filled with approximately 90% Ar and 10% air is provided in the IGUembodiments.

ITO % U-value #4 Emis- Monolithic IGU U-value Thick- Improve- sivityTvis Rvis Tvis Rvis, in COG ness ment 0.84 (no n/a n/a 69.3 12.6 0.247 0n/a coating) 0.20 87.5 8.5 67.4 12.4 0.205 130 17.0% 0.15 86.2 8.5 66.412.4 0.200 195 19.0% 0.10 85.0 8.5 65.5 12.4 0.194 260 21.5% 0.05 80.08.5 61.6 12.0 0.188 520 23.9%

The FIG. 7 example embodiment advantageously is very durable, e.g.,after heat treatment, even though it does not include an overcoat layercomprising ZrOx or the like. It therefore has been found to be suitablefor use as a so-called Surface 4 coating. As is known, the fourthsurface of an IGU, for example, is the surface farthest from the sun(and thus typically facing a building interior). Thus, the FIG. 7example layer stack is particularly well-suited for use in an assemblysimilar to that shown in FIG. 3. It also will be appreciated that theFIG. 7 example embodiment is suitable for use in connection with otherglazings where it is the provided on an innermost surface facing theinterior of the building (e.g., on surface 6 of a triple-IGU, etc.).

As alluded to above, the FIG. 7 example layer stack is heat treatable incertain example embodiments. Such heat treatment may be accomplishedusing an infrared (IR) heater, a box or other furnace, a laser annealingprocess, etc. Further example details of heat treatment are providedbelow. The two tables that follow include performance data for themonolithic FIG. 7 layer stack post-IR heat treatment and post-beltfurnace heat treatment (e.g., at 650 degrees C.), respectively.

Monolithic Annealed (Post IR Treatment) Performance Data

Glass Thickness (mm) 2.8 mm T 88.49 a*, Transmission −0.56 b*,Transmission 0.22 L*, Transmission 95.36 Rg 9.11 a*, Glass Side −0.4 b*,Glass Side −1.13 L*, Glass Side 36.20 Rf 9.10 a*, Film Side −0.72 b*,Film Side −1.13 L*, Film Side 36.17 Transmitted Color Rendering Index(CRI) 97.91 T-Haze 0.12 Surface Roughness 1.8 Sheet Resistance 17-19Hemispherical Emittance 0.20 or 0.21Monolithic Tempered (belt furnace 650) Performance Data

T 88.10 ΔE (Annealed to Tempered) 0.37 a*, Transmission −0.60 b*,Transmission 0.54 L*, Transmission 95.20 Rg 9.08 ΔE (Annealed toTempered) 1.04 a*, Glass Side −0.26 b*, Glass Side −2.16 L*, Glass Side36.14 Rf 9.06 ΔE (Annealed to Tempered) 1.16 a*, Film Side −0.69 b*,Film Side −2.28 L*, Film Side 36.10 Transmitted Color Rendering Index(CRI) 97.91 T-Haze 0.12 Surface Roughness 1.8 Sheet Resistance (NAGY)17-19 Hemispherical Emittance 0.19 or 0.20

As indicated above, the FIG. 7 example embodiment may be heat treatedusing, for example, an infrared (IR) heater, a box or other furnace, alaser annealing process, etc. A post deposition heat treatment step maybe advantageous in helping to re-crystallize the ITO layer and inhelping to achieve the desired emissivity and optics (e.g., includingthose described above). In an example process, the glass may be heatedto a temperature of approximately 400 degrees C. to help meet theseaims. In certain example embodiments, the glass temperature will notexceed 470 degrees C., so as to help reduce the likelihood of permanent(or at least non-temporary) stress changes being introduced in theglass.

Certain example embodiments may use a laser diode array in connectionwith a laser annealing process. It has been found that a laser diodearray with the following parameters advantageously helps reduce thesheet resistance to about 20 ohms/square (from, for example, about 65ohms/square in the as-deposited state), helps achieve a substantiallyuniform coating appearance, and helps meet the above-listed performancemetrics:

-   -   Laser power—1 kW    -   Emission wavelength—975 nm    -   Scan rate—75 mm/sec.    -   Spot size—nominally 12.5 mm×2 mm

A furnace having multiple zones also may be used for heat treatingcertain example embodiments. Zone temperature, line speed, temperaturebias (e.g., top/bottom), aspiration, element trimming (e.g., across thefurnace), cooling air settings (e.g., pressure and flow bias), and/orother factors may be tuned to help achieve the desired performancecharacteristics. In certain example embodiments, a ten-zone furnace maybe used to accomplish the heat treating. A partial subset of the zonesmay help with the ITO re-crystallization process, whereas other zonesmay help to slowly cool the substrate prior to its exit from thefurnace. In one example where a ten-zone furnace was used, zones 1-3were found to be active in the ITO re-crystallization process, heatingthe coating to a temperature near 400 degrees C., whereas the remainderof the furnace helped slowly cool the glass prior to exit into thecooling air sections. It will be appreciated that it would be desirablein certain example instances to maintain a low exit temperature in orderto help reduce the likelihood of breakage. Indeed, glass is verysensitive to thermal breakage over the temperature range involved in there-annealing process, particularly at temperatures over 200 degrees C.

Further parameters influencing thermal breakage include the temperaturedifferential through the glass thickness, as well as the differentialacross its surface. The former was found to have a large impact onthermal breakage with respect to the coated substrates. The top andbottom surface temperatures of uncoated glass exiting the furnace werenearly identical, and the vast majority of clear glass survived theannealing process after the initial profile was established (line speed,zone temp., cooling air, no bias). However, the top surface of thecoated product was measured to be as much as 250 degrees F. higher atthe furnace exit. This is because heat is lost faster through conductivetransfer to the rolls than radiant transfer from the coated top surface.

However, by identifying and understanding this differential and biasingheating and cooling, it is possible to reduce this difference and, inturn, to help reduce the likelihood of breakage. Example furnaceprofiles for 3.2 mm and 2.3 mm glass are provided in the tables below,respectively.

3.2 mm Furnace Profile

Zone Furnace Temp. (F.) 1 2 3 4 5 6 7 8 9 10 Top Setpoint 1420 1420 14200 0 0 0 0 0 0 Actual 1422 1442 1423 937 745 693 565 551 585 581 BottomSetpoint 1420 1420 1420 0 700 700 700 700 700 700 Actual 1440 1438 1431825 780 743 730 453 690 705

The following parameters were used in connection with this exampleheating profile:

-   -   Line Speed: 60 ft/min    -   Aspiration: 0    -   Trim (Zones 1-3): 5-10 (50%)—center, all others 100%    -   Primary Quench: Set point=0 and damper closed    -   Mid-Range Cooling: 1″ H2O, set point=0 and damper open    -   After Cooler: 1″ H2O, set point=0 and damper open

2.3 mm Furnace Profile

Zone Furnace Temp. (F.) 1 2 3 4 5 6 7 8 9 10 Top Setpoint 1420 1420 14200 0 0 0 0 0 0 Actual 1422 1442 1423 937 712 643 544 525 542 570 BottomSetpoint 1420 1420 1420 0 600 600 600 600 600 600 Actual 1440 1438 1431825 644 609 612 386 602 601

The following parameters were used in connection with this exampleheating profile:

-   -   Line Speed: 70 ft/min    -   Aspiration: 0    -   Trim (Zones 1-3): 5-10 (50%)—center, all others 100%    -   Primary Quench: 1″ H2O, top only, set point=0 and damper open    -   Mid-Range Cooling: Set point=0 and damper closed    -   After Cooler: 1″ H2O, set point=0 and damper open

As still another option, wavelength-tuned IR radiation may be used forheat-treating in certain example embodiments. Example techniques are setforth in U.S. patent application Ser. No. 12/923,082, filed Aug. 31,2010, the entire contents of which are hereby incorporated herein byreference. The TCO layer may be preferentially and selectively heattreated using specifically tuned near infrared-short wave infrared(NIR-SWIR) radiation, for example. Selective heating of the coating mayin certain example embodiments be obtained by using IR emitters withpeak outputs over spectral wavelengths where ITO is significantlyabsorbing but where the substrate (e.g., glass) has reduced or minimalabsorption. In certain example embodiments, the coating will bepreferentially heated thereby improving its properties while at the sametime keeping the underlying substrate temperatures low.

By preferentially heating the coating using the high-intensity,wavelength-tuned IR radiation techniques described herein, heattreatment of the ITO layer is possible at lower substrate temperaturesand/or shorter heating times than would be required by conventionalmeans. Preferential heating is achieved by using IR wavelengths that areabsorbed much more strongly by the coating than the substrate. Highintensity IR radiation may be supplied, for example, by quartz lamps orlaser emitters.

In the case of laser emitters, laser diode arrays may be advantageous,e.g., given their lower cost of ownership compared to other common lasertypes (and the availability of about 800-1050 nm (for example, 940 nm)wavelength output matches well with the spectral characteristics of thecoating). However, excimer, CO₂, YAG, quartz, and/or other types oflasers and/or lamps also may be used in different embodiments. Forexample, it is noted that an 810 nm wavelength is common for some diodelasers (and in general may be used in connection with low-E typecoatings, for instance), and that a 1032 nm wavelength is common forsome YAG lasers. Still further, certain example embodiments may useother lasers (e.g., CO₂ or other lasers) to very rapidly heat the glassand thereby indirectly heat the coating. In certain example embodiments,electromagnetic radiation may be focused into a very high aspect ratiorectangular beam spanning the width of the glass. The glass may betraveling on a conveyor in a direction perpendicular to the long axis ofthe rectangle. In certain example embodiments, a “step and repeat”process may be employed, e.g., so as to irradiate smaller sections in acontrolled manner such that the entire substrate ultimately isirradiated. In addition, other sizes and/or shapes may be usedincluding, for example, substantially square shapes, circular shapes,etc.

In general, higher power densities have been found to be preferablebecause they permit shorter heating times and higher temperaturegradients from the coating through the bulk substrate. With shorterheating times, less heat is transferred from the coating through theglass via conduction and a lower temperature may be maintained.

FIG. 8 is a schematic view of a system incorporating an IR heater inaccordance with certain example embodiments. The FIG. 8 example systemincludes a coater 102 for physical vapor depositing one or more thinfilm layers on a substrate, e.g., via sputtering. Downstream of thecoater 102 is an IR heater 104. In certain example embodiments, a roomtemperature sputtering apparatus may be used to deposit ITO on a glasssubstrate. A conveyor system 106 conveys a substrate through the coater102, where the layer or layer stack is deposited, and to the IR heater104. The IR heater 104, in turn, is tuned to focus NIR-SWIR radiation atthe substrate with the coating thereon. The wavelength of the IRradiation is selected to as to preferentially heat the coating or aparticular layer in the coating, e.g., as compared to the substrateand/or any other layers in a multilayer coating.

Although certain example embodiments have been described as including anIR heater downstream of the coater, it will be appreciated thatdifferent example embodiments may locate a coater within a vacuumchamber of the coater. In addition, in certain example embodiments, theIR heat treatment may be performed at any time once the layer to be heattreated or activated has been deposited. For instance, certain exampleembodiments may perform an IR heat treatment just after ITO layerdeposition, whereas certain example embodiments may perform an IR heattreatment once all layers in a layer stack have been deposited. Incertain example embodiments, multiple IR heat treatments may beperformed at different times during the deposition process.

A short-wave infrared (SWIR) furnace incorporating quartz lamps may beused in certain example embodiments. A peak IR emission wavelength of1.15 μm may be used to heat the coating. This wavelength was determinedby analyzing the spectral characteristics of the coating and the glasssubstrate, although other wavelengths of course are possible. Indeed, anexample wavelength range for heating of 0.8-2.5 μm has been determined.More preferably, the IR emission range is 1-2 μm. The techniquesdescribed in U.S. patent application Ser. No. 12/923,082, for example,may be used to establish optimum or preferred IR emission ranges forheat treating other coatings (e.g., other TCO, metallic, etc., coatings)on glass, as well.

The power density of the SWIR furnace is 10.56 kW/ft² (bulb output is 80W/in, with mounting on 1″ centers). Heating times may range from 12-130sec with 12 sec intervals, for example. Heating elements may be about 4″from the glass surface, although the heating elements may be raised orlowered in different example embodiments of this invention.

By targeting IR wavelengths absorbed by the coating, it is possible togenerate a large thermal gradient between the coating and bulksubstrate. Because the thermal mass of the coating is very smallcompared to the glass, the glass essentially acts as a quench mechanism.The rise in bulk glass temperature is mainly attributed to direct heattransfer by IR absorption, rather than by conduction from the coating.

It has been found that the final crystallinity of the film is obtainedafter only 48-60 sec of heating, although short or longer times are ofcourse possible.

The initial oxidation level of the ITO on the samples used herein hasbeen optimized for low sheet resistance following tempering (whichresults in additional oxidation of the ITO). It is likely that adifferent optimum exists for heat treating ITO using NIR radiation. Whenthe initial oxidation level of the ITO is optimized for NIR heating, itshould be possible to significantly reduce the amount of heatingrequired. Theoretically, this time should be reduced to the 48-60 secrequired for re-crystallization using the same heating process. Furtherdecreases is heating time may be achieved by optimizing the powerdensity vs. heating time requirements.

The IR heating techniques described herein preferably preferentiallyheat the ITO in the coating such that the glass substrate remains belowits transition temperature, which is about 480 degrees C. for floatglass. Preferably, the glass substrate remains below 450 degrees C., andmore preferably below 425 degrees C. In certain example embodiments,where a peak emission of 1.15 μm is applied for 108 sec, the sheetresistance of the example coating is about one-third of its as-depositedequivalent, and the emissivity and absorption correspondingly drop toabout one-half of their as-deposited counterpart values. In themeantime, the substrate temperature reaches a maximum of only about 400degrees C., which is well below its transition temperature.

NIR generally includes IR having a wavelength of 0.75-1.4 μm, and SWIRgenerally includes IR having a wavelength of 1.4-3 μm. Certain exampleembodiments may generally operate within these wavelengths. Thesubstrate temperature preferably does not exceed 480 degrees C., morepreferably 450 degrees C., still more preferably 425 degrees C., andsometimes 400 degrees C., as a result of such NIR-SWIR heating.

Although certain example embodiments have been described herein asrelating to anticondensation coatings, the coatings described herein maybe used in connection with other applications. For instance, the examplecoatings described herein may be used in connection withrefrigerator/freezer and/or other merchandizer applications, skylights,etc.

In certain example embodiments, following heat treatment or activationvia the techniques described herein, a coated article may be forwardedto a fabricator or other location, e.g., for further processing such as,for example, cutting, sizing, incorporation into a further article(e.g., a insulating glass unit, skylight, vehicle, glazing, etc.).Preferably, breaking or catastrophic failures of the heat treated coatedarticle will not result as a result of changes to the glass caused bythe heat treatment process.

“Peripheral” and “edge” seals herein do not mean that the seals arelocated at the absolute periphery or edge of the unit, but instead meanthat the seal is at least partially located at or near (e.g., withinabout two inches) an edge of at least one substrate of the unit.Likewise, “edge” as used herein is not limited to the absolute edge of aglass substrate but also may include an area at or near (e.g., withinabout two inches) of an absolute edge of the substrate(s).

As used herein, the terms “on,” “supported by,” and the like should notbe interpreted to mean that two elements are directly adjacent to oneanother unless explicitly stated. In other words, a first layer may besaid to be “on” or “supported by” a second layer, even if there are oneor more layers therebetween.

It will be appreciated that certain example embodiments may incorporateone or more additional low-E coatings on a surface of one or more glasssubstrates facing the air gap therebetween (e.g., surfaces 2 and/or 3 inan IGU; surfaces 2, 3, 4, and/or 5 in a triple-IGU, etc.). A surface 4low-E coating disposed on clear glass, for example, may help improve theoverall window u-value, e.g., by reflecting infrared heat back insidethe building. The glass in certain example embodiments may be 2.3 mm to6 mm clear float glass in certain example embodiments. In suchembodiments, the hemispherical emissivity may be reduced to 0.3 andsheet resistance to 30 ohms/square. Preferably, emissivity may bereduced to 0.23-0.30 and sheet resistance to 30 ohms/square, andsometimes emissivity may be reduced to less than or equal to about 0.2and sheet resistance to less than or equal to about 20 ohms/square.

For instance, as alluded to above, it may be desirable in certainexample scenarios to provide a more durable low-E coating on an outersurface of an IG unit and a potentially less durable low-E coating on aninner surface of the IG unit where it can be protected. One exampleconfiguration, then, would involve a low-E coating being provided toboth sides of a single substrate, e.g., surfaces 1 and 2, or surfaces 3and 4. Of course, other arrangements also are contemplated (e.g., wheresurfaces 1 and 3, or surfaces 2 and 4 are provided with low-E coatings).The low-E coating provided on surface 4 may be a more durable coatingthan the low-E coating provided to surface 3, which is naturallyprotected from the outside environment by virtue of its location withinthe cavity of the IG unit. The low-E coating provided on surface 4 maybe any of the coatings described above, e.g., in connection with FIGS.1, 6, and 7. The low-E coating provided on surface 3 may have a SHGCsufficient to reduce overall the U-value of the IG unit to a desiredlevel (e.g., that complies with the 0.30/.30 standard noted above). Incertain example embodiments, the interior facing low-E coating may be asilver-based low-E coating, whereas the low-E coating exposed to theexterior surface may be an ITO-based coating.

The above-listed silver-based low-E coatings may be used on FIG. 3 forthis purpose. Other suitable low-E coatings that may be used on theinterior surface include the example coatings set forth below.

FIRST EXAMPLE Ag-Based Low-E Coating

Example Example Material Preferred More Preferred Thickness 1 Thickness2 Glass Thickness (Å) Thickness (Å) (Å) (Å) Si_(x)N_(y)  1-500 100-300160 160 TiO_(x) 75-125  85-115 100 100 ZnO 35-75  40-70 60 50 SnO 35-200 50-135 100 70 ZnO 30-200  40-130 60 100 Ag 60-110  70-100 85 85 NiCrOx20-40  23-37 30 30 SnO 150-275  170-255 220 200 Si_(x)N_(y)  1-1000100-500 220 250

SECOND EXAMPLE Ag-Based Low-E Coating

Example Example Material Preferred More Preferred Thickness 1 Thickness2 Glass Thickness (Å) Thickness (Å) (Å) (Å) Si_(x)N_(y)  1-500  10-300156 156 TiO_(x) 15-50  30-40 33 35 ZnO 70-200  95-125 114 110 TiO_(x)15-50  30-40 33 35 ZnO 70-200  95-125 114 110 Ag 70-120  80-100 90 90NiCrOx  1-100 10-50 30 30 SnO 110-150  115-145 130 130 ZnO 70-200 95-125 109 109 Si_(x)N_(y) 115-185  125-155 140 140 ZrO_(x)  1-20010-80 40 40

Further details regarding the first and second example Ag-based low-Ecoatings discussed above are set forth in detail in U.S. applicationSer. No. 13/333,069, filed on Dec. 21, 2011, and which is herebyincorporated herein by reference in its entirety.

THIRD EXAMPLE Ag-Based Low-E Coating

Example Example Material Preferred More Preferred Thickness 1 Thickness2 Glass Thickness (Å) Thickness (Å) (Å) (Å) Si_(x)N_(y)  1-500 10-300135 140 TiO_(x) 60-110 65-100 80 85 Si_(x)N_(y) 50-90  55-80  65 70ZnO_(x) or 60-110 70-100 85 85 ZnAlO_(x) Ag 60-110 65-100 80 85NiCrO_(x) 22-42  25-38  30 33 SnO_(x) 125-215  145-195  170 170Si_(x)N_(y)  1-500 10-300 170 170

FOURTH EXAMPLE Ag-Based Low-E Coating

Example Example Material Preferred More Preferred Thickness 1 Thickness2 Glass Thickness (Å) Thickness (Å) (Å) (Å) TiO_(x) 135-250 150-230 200180 SnO_(x)  0-40  1-30 — 20 (optional) ZnO_(x) or 30-63 33-60 40 50ZnAlO_(x) Ag 100-170 115-155 135 135 NiCrO_(x)  1-100 10-50 30 30TiO_(x) 30-50 35-45 40 40 ZnO_(x) 120-200 135-185 160 160 Si_(x)N_(y) 1-500 100-300 210 210

FIFTH EXAMPLE Ag-Based Low-E Coating

Example Example Material Preferred More Preferred Thickness 1 Thickness2 Glass Thickness (Å) Thickness (Å) (Å) (Å) TiO_(x) 120-210 140-190 165165 ZnO_(x) or  60-100 65-95 80 80 ZnAlO_(x) Ag 155-260 175-240 208 208NiCrO_(x)  1-100 10-50 30 30 TiO_(x) 30-50 35-45 40 40 SnO_(x) 220 149Si_(x)N_(y)  1-500 100-400 250 322

SIXTH EXAMPLE Ag-Based Low-E Coating

Material Preferred More Preferred Example Glass Thickness (Å) Thickness(Å) Thickness (Å) TiO_(x) 120-210  140-190 165 Si_(x)N_(y) 1-500  30-300100 ZnO_(x) or 60-100  65-95 80 ZnAlO_(x) Ag 75-125   85-115 100NiCrO_(x) 1-100 10-50 35 TiO_(x) 33-60  38-52 45 SnO_(x) 120-200 135-185 160 Si_(x)N_(y) 1-500  50-350 180 ZrO_(x) 1-100  5-50 20

In certain example embodiments, an insulating glass (IG) unit isprovided. First and second substantially parallel spaced apart glasssubstrates are provided, with the first and second substrates providing,in order, first through fourth substantially parallel major surfaces ofthe IG unit. A gap is defined between the first and second substrates. Afourth surface of the IG unit supports a first low-E coating comprisinga plurality of thin film layers including, in order moving away from thesecond substrate: a first layer comprising silicon oxynitride having anindex of refraction of 1.5-2.1 and being 50-90 nm thick, a layercomprising ITO having an index of refraction of 1.7-2.1 and being 85-125nm thick, and a second layer comprising silicon oxynitride having anindex of refraction of 1.5-2.1 and being 50-90 nm thick.

In addition to the features of the previous paragraph, in certainexample embodiments, the first and second layer comprising siliconoxynitride may have indices of refraction of 1.7-1.8.

In addition to the features of either of the two prior paragraphs, incertain example embodiments, the layer comprising ITO may have an indexof refraction of 1.8-1.93.

In addition to the features of any of the previous three paragraphs, incertain example embodiments, the first and second layers comprisingsilicon oxynitride may have indices of refraction and thicknesses thatvary from one another by no more than 0.1 and 10 nm, respectively.

In addition to the features of any of the previous four paragraphs, incertain example embodiments, the third surface of the IG unit maysupport a second low-E coating comprising a plurality of thin filmlayers including, in order moving away from the second substrate: afirst silicon-based layer; a first dielectric layer; a second dielectriclayer split by a third dielectric layer so as to form first and secondportions of the second dielectric layer; a metallic or substantiallymetallic infrared (IR) reflecting layer over and directly contacting thesecond portion of the second dielectric layer; an upper contact layercomprising an oxide of Ni and/or Cr directly over and contacting the IRreflecting layer; a fourth dielectric layer; and a second silicon-basedlayer. The third dielectric layer may comprise either titanium oxide ortin oxide.

In addition to the features of the previous paragraph, in certainexample embodiments, the first dielectric layer may be a high refractiveindex layer comprising an oxide or sub-oxide of titanium.

In addition to the features of either of the two prior paragraphs, incertain example embodiments, the third and fourth dielectric layers maycomprise tin oxide.

In addition to the features of the previous paragraph, in certainexample embodiments, the second dielectric layer may comprise zincoxide.

In addition to the features of the previous paragraph, in certainexample embodiments, the second layer may be split such that the partsthereof have thicknesses that vary by no more than 5% of one another.

In addition to the features of any of the previous five paragraphs, incertain example embodiments, the first and second silicon-based layersmay each comprise silicon nitride, the first dielectric layer maycomprise titanium oxide, the second dielectric layer may comprise zincoxide, the third and fourth dielectric layers may each comprise tinoxide, and the IR reflecting layer may comprise Ag.

In addition to the features of any of the previous six paragraphs, incertain example embodiments, the second substrate may be heat treatedwith the first and/or second low-E coatings disposed thereon.

In addition to the features of any of the previous seven paragraphs, incertain example embodiments, the second low-E coating may have a SHGCsufficient to bring the U-value of the IG unit to less than or equal to0.30.

In certain example embodiments, there is provided a coated articlecomprising a substrate supporting first and second low-E coatings onopposing major surfaces thereof, respectively. The first low-E coatingcomprises, in order moving away from the substrate: a first layercomprising silicon oxynitride having an index of refraction of 1.5-2.1and being 50-90 nm thick, a layer comprising ITO having an index ofrefraction of 1.7-2.1 and being 85-125 nm thick, and a second layercomprising silicon oxynitride having an index of refraction of 1.5-2.1and being 50-90 nm thick. The second low-E coating comprises, in ordermoving away from the substrate: a first silicon-based layer, a firstdielectric layer, a second dielectric layer split by a third dielectriclayer so as to form first and second portions of the second dielectriclayer, the third dielectric layer comprising either titanium oxide ortin oxide, a metallic or substantially metallic infrared (IR) reflectinglayer over and directly contacting the second portion of the seconddielectric layer, an upper contact layer comprising an oxide of Niand/or Cr directly over and contacting the IR reflecting layer, a fourthdielectric layer, and a second silicon-based layer.

In certain example embodiments, a method of making an insulating glassunit (IGU) is provided. A first glass substrate is provided. A firstlow-E coating is disposed, directly or indirectly, on a first majorsurface of the first glass substrate. The first low-E coating comprisesa plurality of thin film layers including, in order moving away from thefirst glass substrate: a first layer comprising silicon oxynitride, alayer comprising ITO, and a second layer comprising silicon oxynitride.A second glass substrate is provided in substantially parallel, spacedapart relation to the first glass substrate such that the first majorsurface of the first glass substrate faces away from the second glasssubstrate. The first substrate with only the first low-E coating thereonhas a hemispherical emissivity of less than or equal to about 0.20 and asheet resistance less than or equal to about 20 ohms/square followingheat treatment. The first major surface of the first glass substratecorresponds to an interior surface of the IGU.

In addition to the features of the previous paragraph, in certainexample embodiments, a second low-E coating may be disposed, directly orindirectly, on a second major surface of the first glass substrateopposite to the first second major surface of the first glass substrate.The second low-E coating may comprise a plurality of thin film layersincluding, in order moving away from the first glass substrate: a firstsilicon-based layer; a first dielectric layer; a second dielectric layersplit by a third dielectric layer so as to form first and secondportions of the second dielectric layer, the third dielectric layercomprising either titanium oxide or tin oxide; a metallic orsubstantially metallic infrared (IR) reflecting layer over and directlycontacting the second portion of the second dielectric layer; an uppercontact layer comprising an oxide of Ni and/or Cr directly over andcontacting the IR reflecting layer; a fourth dielectric layer; and asecond silicon-based layer.

In addition to the features of the previous paragraph, in certainexample embodiments, the first dielectric layer may be a high refractiveindex layer comprising an oxide or sub-oxide of titanium.

In addition to the features of either of the two prior paragraphs, incertain example embodiments, the third and fourth dielectric layers maycomprise tin oxide.

In addition to the features of the previous paragraph, in certainexample embodiments, the second dielectric layer may comprise zincoxide.

In addition to the features of the previous paragraph, in certainexample embodiments, the second layer may be split such that the partsthereof have thicknesses that vary by no more than 5% of one another.

In addition to the features of any of the previous five paragraphs, incertain example embodiments, the first and second silicon-based layersmay each comprise silicon nitride, the first dielectric layer maycomprise titanium oxide, the second dielectric layer may comprise zincoxide, the third and fourth dielectric layers may each comprise tinoxide, and the IR reflecting layer may comprise Ag.

In addition to the features of any of the previous six paragraphs, incertain example embodiments, the first substrate may be heat treatedwith the first and/or second low-E coatings disposed thereon.

In addition to the features of any of the previous seven paragraphs, incertain example embodiments, the second low-E coating may have a SHGCsufficient to bring the U-value of the IG unit to less than or equal to0.30.

While the invention has been described in connection with what ispresently considered to be the most practical and preferred embodiment,it is to be understood that the invention is not to be limited to thedisclosed embodiment, but on the contrary, is intended to cover variousmodifications and equivalent arrangements included within the spirit andscope of the appended claims.

What is claimed is:
 1. An insulating glass (IG) unit, comprising: firstand second substantially parallel spaced apart glass substrates, thefirst and second substrates providing, in order, first through fourthsubstantially parallel major surfaces of the IG unit, a gap beingdefined between the first and second substrates; wherein a fourthsurface of the IG unit supports a first low-E coating comprising aplurality of thin film layers including, in order moving away from thesecond substrate: a first layer comprising silicon oxynitride having anindex of refraction of 1.5-2.1 and being 50-90 nm thick, a layercomprising ITO having an index of refraction of 1.7-2.1 and being 85-125nm thick, and a second layer comprising silicon oxynitride having anindex of refraction of 1.5-2.1 and being 50-90 nm thick.
 2. The IG unitof claim 1, wherein the first and second layer comprising siliconoxynitride have indices of refraction of 1.7-1.8.
 3. The IG unit ofclaim 2, wherein the layer comprising ITO has an index of refraction of1.8-1.93.
 4. The IG unit of claim 1, wherein the layer comprising ITOhas an index of refraction of 1.8-1.93.
 5. The IG unit of claim 1,wherein the first and second layers comprising silicon oxynitride haveindices of refraction and thicknesses that vary from one another by nomore than 0.1 and 10 nm, respectively.
 6. The IG unit of claim 1,wherein the third surface of the IG unit supports a second low-E coatingcomprising a plurality of thin film layers including, in order movingaway from the second substrate: a first silicon-based layer; a firstdielectric layer; a second dielectric layer split by a third dielectriclayer so as to form first and second portions of the second dielectriclayer; a metallic or substantially metallic infrared (IR) reflectinglayer over and directly contacting the second portion of the seconddielectric layer; an upper contact layer comprising an oxide of Niand/or Cr directly over and contacting the IR reflecting layer; a fourthdielectric layer; and a second silicon-based layer, wherein the thirddielectric layer comprises either titanium oxide or tin oxide.
 7. The IGunit of claim 6, wherein the first dielectric layer is a high refractiveindex layer comprising an oxide or sub-oxide of titanium.
 8. The IG unitof claim 6, wherein the third and fourth dielectric layers comprise tinoxide.
 9. The IG unit of claim 8, wherein the second dielectric layercomprises zinc oxide.
 10. The IG unit of claim 9, wherein the secondlayer is split such that the parts thereof have thicknesses that vary byno more than 5% of one another.
 11. The IG unit of claim 6, wherein thefirst and second silicon-based layers each comprise silicon nitride, thefirst dielectric layer comprises titanium oxide, the second dielectriclayer comprises zinc oxide, the third and fourth dielectric layers eachcomprise tin oxide, and the IR reflecting layer comprises Ag.
 12. The IGunit of claim 6, wherein the second substrate is heat treated with thefirst and/or second low-E coatings disposed thereon.
 13. The IG unit ofclaim 6, wherein the second low-E coating has a SHGC sufficient to bringthe U-value of the IG unit to less than or equal to 0.30.
 14. A coatedarticle comprising a substrate supporting first and second low-Ecoatings on opposing major surfaces thereof, respectively, wherein: thefirst low-E coating comprises, in order moving away from the substrate:a first layer comprising silicon oxynitride having an index ofrefraction of 1.5-2.1 and being 50-90 nm thick, a layer comprising ITOhaving an index of refraction of 1.7-2.1 and being 85-125 nm thick, anda second layer comprising silicon oxynitride having an index ofrefraction of 1.5-2.1 and being 50-90 nm thick; and the second low-Ecoating comprises, in order moving away from the substrate: a firstsilicon-based layer, a first dielectric layer, a second dielectric layersplit by a third dielectric layer so as to form first and secondportions of the second dielectric layer, the third dielectric layercomprising either titanium oxide or tin oxide, a metallic orsubstantially metallic infrared (IR) reflecting layer over and directlycontacting the second portion of the second dielectric layer, an uppercontact layer comprising an oxide of Ni and/or Cr directly over andcontacting the IR reflecting layer, a fourth dielectric layer, and asecond silicon-based layer.